4 * This file is part of BeRTOS.
6 * Bertos is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
20 * As a special exception, you may use this file as part of a free software
21 * library without restriction. Specifically, if other files instantiate
22 * templates or use macros or inline functions from this file, or you compile
23 * this file and link it with other files to produce an executable, this
24 * file does not by itself cause the resulting executable to be covered by
25 * the GNU General Public License. This exception does not however
26 * invalidate any other reasons why the executable file might be covered by
27 * the GNU General Public License.
29 * Copyright 2001, 2004 Develer S.r.l. (http://www.develer.com/)
30 * Copyright 1999, 2000, 2001, 2008 Bernie Innocenti <bernie@codewiz.org>
33 * \brief Process scheduler (public interface).
36 * \author Bernie Innocenti <bernie@codewiz.org>
41 #include "cfg/cfg_kern.h"
42 #include <cfg/compiler.h>
44 #if CONFIG_KERN_PREEMPT
45 #include <cfg/debug.h> // ASSERT()
48 #include <cpu/types.h> // cpustack_t
51 * Forward declaration. The definition of struct Process is private to the
52 * scheduler and hidden in proc_p.h.
56 /* Task scheduling services */
58 struct Process *proc_new_with_name(const char* name, void (*entry)(void), iptr_t data, size_t stacksize, cpustack_t *stack);
60 #if !CONFIG_KERN_MONITOR
61 #define proc_new(entry,data,size,stack) proc_new_with_name(NULL,(entry),(data),(size),(stack))
63 #define proc_new(entry,data,size,stack) proc_new_with_name(#entry,(entry),(data),(size),(stack))
67 void proc_yield(void);
68 #define proc_switch proc_yield /* OBSOLETE */
70 int proc_testSetup(void);
71 int proc_testRun(void);
72 int proc_testTearDown(void);
74 struct Process *proc_current(void);
75 iptr_t proc_currentUserData(void);
76 void proc_rename(struct Process *proc, const char *name);
77 const char *proc_name(struct Process *proc);
78 const char *proc_currentName(void);
81 * Disable preemptive task switching.
83 * The scheduler maintains a global nesting counter. Task switching is
84 * effectively re-enabled only when the number of calls to proc_permit()
85 * matches the number of calls to proc_forbid().
87 * \note Calling functions that could sleep while task switching is disabled
88 * is dangerous and unsupported.
90 * \note proc_permit() expands inline to 1-2 asm instructions, so it's a
91 * very efficient locking primitive in simple but performance-critical
92 * situations. In all other cases, semaphores offer a more flexible and
93 * fine-grained locking primitive.
97 INLINE void proc_forbid(void)
99 #if CONFIG_KERN_PREEMPT
100 // No need to protect against interrupts here.
101 extern int preempt_forbid_cnt;
102 ++preempt_forbid_cnt;
105 * Make sure preempt_forbid_cnt is flushed to memory so the
106 * preemption softirq will see the correct value from now on.
113 * Re-enable preemptive task switching.
117 INLINE void proc_permit(void)
119 #if CONFIG_KERN_PREEMPT
122 * This is to ensure any global state changed by the process gets
123 * flushed to memory before task switching is re-enabled.
127 /* No need to protect against interrupts here. */
128 extern int preempt_forbid_cnt;
129 --preempt_forbid_cnt;
130 ASSERT(preempt_forbid_cnt >= 0);
133 * This ensures preempt_forbid_cnt is flushed to memory immediately
134 * so the preemption interrupt sees the correct value.
143 * Execute a block of \a CODE atomically with respect to task scheduling.
145 #define PROC_ATOMIC(CODE) \
152 #ifndef CONFIG_KERN_MINSTACKSIZE
154 #if (ARCH & ARCH_EMUL)
155 /* We need a large stack because system libraries are bloated */
156 #define CONFIG_KERN_MINSTACKSIZE 65536
159 * Default stack size for each thread, in bytes.
161 * The goal here is to allow a minimal task to save all of its
162 * registers twice, plus push a maximum of 32 variables on the
165 * The actual size computed by the default formula is:
171 * Note that on most 16bit architectures, interrupts will also
172 * run on the stack of the currently running process. Nested
173 * interrupts will greatly increases the amount of stack space
174 * required per process. Use irqmanager to minimize stack
177 #define CONFIG_KERN_MINSTACKSIZE \
178 (CPU_SAVED_REGS_CNT * 2 * sizeof(cpustack_t) \
183 #define CONFIG_PROC_DEFSTACKSIZE CONFIG_KERN_MINSTACKSIZE // OBSOLETE
185 /* Memory fill codes to help debugging */
186 #if CONFIG_KERN_MONITOR
187 #include <cpu/types.h>
188 #if (SIZEOF_CPUSTACK_T == 1)
189 /* 8bit cpustack_t */
190 #define CONFIG_KERN_STACKFILLCODE 0xA5
191 #define CONFIG_KERN_MEMFILLCODE 0xDB
192 #elif (SIZEOF_CPUSTACK_T == 2)
193 /* 16bit cpustack_t */
194 #define CONFIG_KERN_STACKFILLCODE 0xA5A5
195 #define CONFIG_KERN_MEMFILLCODE 0xDBDB
196 #elif (SIZEOF_CPUSTACK_T == 4)
197 /* 32bit cpustack_t */
198 #define CONFIG_KERN_STACKFILLCODE 0xA5A5A5A5UL
199 #define CONFIG_KERN_MEMFILLCODE 0xDBDBDBDBUL
200 #elif (SIZEOF_CPUSTACK_T == 8)
201 /* 64bit cpustack_t */
202 #define CONFIG_KERN_STACKFILLCODE 0xA5A5A5A5A5A5A5A5ULL
203 #define CONFIG_KERN_MEMFILLCODE 0xDBDBDBDBDBDBDBDBULL
205 #error No cpustack_t size supported!
209 #endif /* KERN_PROC_H */